Corrosion inhibiting with ethoxylated aqueous amine dispersions



United States Patent 3,418,254 CORROSION INHIBITING WITH ETHOXYLATED AQUEOUS AMINE DISPERSIONS Chester A. Bishof, Glenside, Pa., and Ronald M. Silverstein, Parsippany, N.J., assignors to Betz Laboratories, Inc., Philadelphia, Pa., a corporation of Pennsylvania N0 Drawing. Filed Oct. 23, 1965, Ser. No. 504,065

9 Claims. (Cl. 252392) ABSTRACT OF THE DISCLOSURE The present invention relates to improved aqueous dispersions of amines, and particularly to the use of such dispersions as corrosion inhibitors in the steam and/or condensate of boiler systems.

Primary aliphatic fatty amines as disclosed by US. Patent 2,460,259, to Kahler, are favored corrosion inhibitors for use in boiler systems. The preferred amines comprise primary aliphatic amines having carbon chain lengths of between 10 and 24 carbon atoms. It is believed that these compositions function by depositing upon the internal surfaces of the metal components of the boiler system a protective film which is resistant to penetration by the corrosive elements of the steam and condensate. At any rate, the dispersion of such agents within the steam and/or condensate greatly reduces the corrosion which is otherwise experienced by these metal components.

In the use of these amines it is essential that the quantity employed be slight in order to permit the treatment of the boiler at a reasonable and acceptable cost. At the same time, the small quantity of the amines which is employed must be uniformly dispersed throughout the boiler system in order to insure adequate protection.

Since these amines are solids at room temperature they must first be transformed to a liquid state. In addition, the liquid form introduced to the boiler system must be such that a constant and uniform feed may be maintained to the high pressure system, and uniformly dispersed therein. As a consequence, aqueous dispersions of the amines have been adopted for this purpose, and in order to obtain such dispersions the use of emulsifiers has been accepted. For example, the use of polyethoxylated amines as emulsifiers for the fatty amine corrosion inhibitors is disclosed by U.S. 3,203,904, to Brown, While ethoxylated quaternary ammonium emulsifiers are disclosed by US. 3,088,796, to Kahler. However, the use of emulsifier is accompanied by several impediments. In the first instance, the emulsifiers do not directly contribute to corrosion inhibition and their presence is undesirable in that they constitute objectionable, extraneous or foreign material which may form deposits within the boiler system. Consequently, it is necessary to maintain the emulsifier at a relatively low level in the amine: emulsifier system. In addition, the aqueous dispersions of the amines are extremely difficult to inject within high pressure system unless employed in a form characterized by low viscosities, while additional problems in respect to storage, handling, metering and feeding are experienced when dispersions having high viscosities are used. Accordingly, the use of these amines is hampered by opposed or conflicting de mands in that the use of high emulsifier contents yields "ice undesirable deposits of foreign material within the boiler system, whereas dispersions possessing satisfactory viscosity cannot be achieved Without the use of quantities of emulsifiers which are undesirably high. To further increase the demands upon such a system, it is preferable to employ dispersions containing increased ratios of the corrosion inhibiting amine. However, this requirement also increases the quantity of emulsifier required for acceptable viscosities, while the necessity for avoiding the introduction of additional foreign materials limits the quantity of emulsifier which may be used. As a consequence, the dispersions employed contain a less than satisfactory proportion of the amines, a quantity of emulsifier which yields excessive deposits of non-functional foreign material within the boiler system, and are characterized by undesirably high viscosities.

It is an object of the present invention to provide improved methods for inhibiting the corrosion of boiler systems by means of low viscosity aqueous dispersions of aliphatic primary amines.

A further object is the provision of boiler corrosion inhibiting compounds characterized by unusually low viscosities.

Another object is the provision of corrosion inhibiting compounds which are characterized by low viscosities, high amine contents, and low emulsifier or foreign material contents.

An additional object is the provision of corrosion inhibiting compounds which are possessed of satisfactory viscosities but which realize economic benefits both as the result of a reduction in the quantity of emulsifier required to achieve such viscosities, and the lower cost of these emulsifiers.

Other objects are hereafter provided by the specification and claims.

The objects of the invention are achieved by means of the emulsification of the primary aliphatic amines with oxyalkylated alcohols.

The primary aliphatic amines employed in the practice of the invention are those fatty amines containing between 10 to 24 carbon atoms in the aliphtic hydrocarbon chain. Typical of such amines are docosylamine, eicosylamine, hexadecylamine, tetradecylamine, laurylami'ne, behenylamine, and the like, although octadecylamine is preferred.

The alkoxylated alcohols employed in the practice of the invention are alkylphenoxypoly (ethyleneoxy) alkanols which may be prepared by the reaction of an alkyl or dialkyl phenol with ethylene oxide, and specifically those alcohols in which the ethylene oxide content is between 60 to percent by weight. These alcohols are represented by the formula:

in which R is an alkyl radical having between 6 to 12 carbon atoms in the aliphatic carbon chain, n is an integer having a value of between 1 to 2, and x is an integer having a value such that the molecule contains an ethyleneoxy content of between 60 to 95 percent by weight.

A preferred ethoxylated alcohol is nonylphenoxypoly (ethyleneoxy) ethanol having the formula:

In addition, the ethyleneoxy alcohols generally are preferred, although similar propyleneoxy and butyleneoxy alcohols may be used in admixture with the ethoxylated alcohols. Other typical alcohols are the hexyl, octyl and dodecyl phenoxy (ethyleneoxy) alkanols such as octyl phenoxy (ethyleneoxy) ethanol, dialkyl compounds such as dinonyl phenoxy (ethyleneoxy) ethanol, and the like. It must be noted that it has been found that the emulsifiers of the invention yield satisfactory results when the ethyleneoxy content of the particular emulsifier comprises between 60 to 95 percent of the composition. Accordingly, as the weight of the alkaryl segment of the molecular is increased, e.g., due to the use of dialkyl phenols or alkyl phenols in which the aliphatic alkyl substituent has a long carbon chain, the length of the ethyleneoxy chain is also increased. For example, in the case of nonyl phenoxy (ethyleneoxy) ethanol, the ethylene oxide content should be at least 7 moles and preferably 30 to 60 moles.

The emulsions of the invention may be prepared by combining the fatty amine and emulsifier, heating the admixture (130160 F.) with agitation until a smooth molten blend is achieved, and slowly adding the water with further agitation. The water added is preferably heated to 130-160" F. prior to addition, and agitation of the emulsion is preferably maintained until the temperature of the emulsion has decreased to 120 F. by cooling.

It should be noted that the emulsions of the present invention may be prepared, stored, and shipped as concentrated emulsions having a high solids content. However, for introduction to a boiler system the emulsions should be diluted to a concentration of between 1 to 60 percent solids, and preferably 2 to 25 percent by weight of solids.

While the use of high emulsifier ratios also yields emulsions of satisfactory viscosities, the quantity of emulsifier must be maintained at a level of no more than a 1:1 weight ratio with the fatty amine, in order to avoid the introduction of excessive and undesirable foreign material within the boiler system. Preferably, the emulsifier comprises between 1 to 30 percent by weight of the amine: emulsifier system, and may be used at levels as low as 0.5 percent by weight of the amine: emulsifier system.

In the treatment of boiler systems with the emulsions of the present invention, the quantity of treatment is based upon the quantity of amine which is introduced within the boiler system. The quantity of amine introduced is preferably between 0.1 to 100 parts by weight per million parts by weight of the steam and/or condensate, or 0.00001 to 0.01 percent by weight.

For the purposes of the present invention, the boiler system which is treated with the inventive compositions constitutes those elements which are contacted by steam or condensate and includes such elements as steam lines, condensate return lines, traps, hot wells, fittings, valves and the like.

The emulsions of the invention are preferably introduced to the steam header of the boiler for uniform distribution. The introduction may be achieved by means of a piston pump of a capacity greater than the internal pressure of the boiler, and may be conducted continuously or at intervals adequate to maintain the desired treatment level. In addition, the boiler may be treated at plural points, e.g., steam header and condensate return lines, and the treatment may be confined to the steam alone, or the condensate alone, or both may be treated.

To demonstrate the ideal viscosities of the inventive emulsions, and the attainment of these viscosities at low emulsifier ratios and relatively high amine contents, the following tests were conducted.

For the purposes of all of the following tests, the

ethoxylated alcohol employed was nonylphenoxypoly (ethyleneoxy) ethanol containing 40 moles of ethylene oxide; the polyethoxylated acid was polyethoxylated stearic acid containing 40 moles of ethylene oxide; the polyethoxylated quaternary compound was the methyl chloride quaternary of polyethoxylated stearylamine containing moles of ethylene oxide; and the polyethoxylated amine was polyethoxylated stearylamine containing 50 moles of ethylene oxide. The amine emulsified in all of the following tests was octadecylamine.

Table 1 demonstrates the low viscosities achieved with the ethoxylated alcohols of the present invention, as contrasted with ethoxylated acids, quaternaries and amines,

when the same quantity of emulsifier is employed in an emulsion containing five percent by weight of total solids:

Table 1 Emulsion (4.5% Oct-adecylamine, Viscosity (Centi- 95% water): poiseBrookfield) Ethoxylated alcohol (0.5%) 350 .Ethoxylated acid 0.5%) Ethoxylated quaternary compounds (0.5% 6,000 Ethoxylated amine (0.5 10,000

The above table demonstrates that viscosity reductions of between 93-965 percent are realized by the present invention and that the viscosities of the contrasted materials are between 14 to 30 times as great as the viscosities realized when the same quantity of the inventive emulsifier is employed. At the same time, the ideally low viscosity was achieved in an emulsion containing only 0.5 percent by weight of emulsifier in which the emulsifier comprised only 10 percent by weight of the total solids.

Table 2 demonstrates the efficacy of the inventive emulsifiers When employed in a ratio of 12 percent by weight of total solids (88:12; octadecylamine: ethoxylated alcohol) in an emulsion containing 15 percent by weight of total solids:

Table 2 Emulsion (13.2% octadecylamine, water):

Viscosity (Centipoise-Brookfield) Ethoxylated alcohol (1.8%) 10,000 Ethoxylated acid (1.8%) 45,000 Ethoxylated quaternary compound (1.8%) 55,000 Ethoxylated amine (1.8%) 85,000

Emulsion (12% octadecylamine, 85% water):

Viscosity Centipoise-Brookfield) Ethoxylated alcohol (3%) 14,000 Ethoxylated acid (3%) 54,000 Ethoxylated quaternary compound (3%) 62,000 Ethoxylated amine (3%) 50,000

Again, the inventive emulsifiers yielded viscosity reductions of between 72 to 77 percent.

The average viscosity of each type of emulsifier in emulsions containing 15 percent by weight of solids was also determined for emulsifier contents varying between 10 to 30 percent by weight of the total solids, and is shown by Table 4.

Table 4 Emulsion (85% water,10.5 13.5% octadecyl'amine) Viscosity (CentipoiseBrookfield) Ethoxylated alcohol (LS-4.5%) 12,160 Ethoxylated acid (LS-4.5%) 53,000 Ethoxylated quaternary compound (LS-4.5%) 58,300 Ethoxylated amine (LS-4.5%) 55,000

The results of Table 4 again show viscosity reduction of between 77 to 79 percent.

In addition, each of the four types of emulsifier was employed in an emulsion containing 25 percent by weight of solids, in quantities of 12, 16 and 20 percent of the total weight of solids (3, 4 and 5 percent by weight of emulsifier in the total system). In all instances, the ethoxylated acid, quaternary compound and amine emulsifiers yielded emulsions having viscosities in excess of 100,000 cps., whereas the emulsions employing 3, 4 and 5 percent of the inventive emulsifier yielded viscosities of 35,000, 30,000 and 26,000 respectively.

In the tests discussed above, viscosities were determined by means of a Brookfield model LVF viscometer and the emulsions were prepared by mixing the octadecylamine and emulsifiers, heating the admixture of 160 F. with agitation, adding the water (heated to 150 F.) to the blend and agitating until the emulsion had cooled to 120 F.

Emulsions of fatty amines employing ethoxylated alcohols as dispersant aids exhibits extremely good corrosion protection when introduced to boiler systems. While emulsions employing octadecylamine and nonylphenoxypoly (ethyleneoxy) ethanol yielded outstanding corrosion inhibition, combinations of other amines, e.g., behenylamine and hexadecylamine, and other alcohols, e.g., dioctyl phenoxypoly (ethyleneoxy) ethanol, and hexyl phenoxypoly (ethyleneoxy) ethanol, also provide satisfactory corrosion inhibition.

In order to demonstrate the stability of the low viscosity emulsions of the invention, the following tests were conducted. In these tests, emulsions were prepared as previousy described in varying solids contents, and were observed after standing for 24 hours. A rating of good indie-ates visible uniformity while fair emulsions exhibited slight non-uniformity, and those characterized by a gritty or badly non-uniform appearance were deemed poor. However, no poor emulsions were yielded by the test.

The test, the results of which are shown by Table 5, employed octadecylamine as the fatty amine, and nonylphenoxy (ethyleneoxy) ethanol (30 moles, ethylene oxide content) as the ethoxylated alcohol. Similar results were obtained with the same alcohol having a 50 mole ethylene oxide content.

Thus it may 'be seen that corrosion inhibiting compositions yielding unusual properties, and their use, have been contributed by the present invention. Specially, the invention provides emulsions of fatty amines which are characterized by an extremely low viscosity. At the same time, the realization of low viscosities in emulsions employing a low emulsifier ratio permits the use of boiler corrosion inhibiting compositions relatively free from ingredients which do not directly contribute to corrosion inhibition but which may create deposition problems Within the boiler. In addition, reduced viscosities permit the use of emulsions containing a greater quantity of the functional ingredient, i.e., the corrosion inhibiting fatty amine. Finally, reduced costs are made possible both by virtue of the reduction in the quantity of emulsifier required, and because of the lower cost of the emulsifiers employed "by the invention. As the result of the low viscosity of these emulsions, and the high amine, low emulsifier systems which are made possible, the corrosion inhibiting agent may be readily and uniformly dispersed within the steam and/or condensate of the boiler system to yield a uniform, economical and eflicient protection, without the problems caused by the introduction of foreign, non-inhibiting materials.

It is apparent that various changes, modifications and substitutions may be made in the compositions and methods of the invention without departing from the spirit of the invention as defined by the following claims.

with an alkylphenoxypoly (ethyleneoxy) alkanol having the formula in which R is an alkyl radical containing between 6 to 12 carbon atoms, n is an integer having a value of between 1 to 2, and x is an integer having a value such that said ethoxylated alcohol has an ethyleneoxy content of between 60 to 95 percent by weight, said .amine being present in a quantity of between 0.00001 to 0.01 percent by weight of said steam and said condensate and said alkanol being present in a quantity of between 0.5 to 50 percent by weight of the total weight of said amine and said alcohol, and contacting said metal components with said steam and said condensate containing said amine.

2. A method as claimed by claim 1 in which said alkylphenoxypoly (ethyleneoxy) alkanol is nonylphenoxypoly (ethyleneoxy) ethanol.

3. A method as claimed by claim 1 in which said primary aliphatic amine is octadecylamine.

4. A method as claimed 'by claim 1 in which said emulsion contains between 1 to 60 percent by weight of said amine and said alkanol.

5. A corrosion inhibiting composition consisting essentially of an aqueous dispersion of between 1 to 60 percent by weight of a primary aliphatic fatty amine containing between 10 to 24 carbon atoms in the aliphatic hydrocarbon chain, and an alkylphenoxypoly (ethyleneoxy) alkanol having the formula in which R is an alkyl radical containing between 6 to 12 carbon atoms, 11 is an integer having a value of between 1 to 2, and x is an integer having a value such that said ethoxylated alcohol has an ethyleneoxy content of between 60 to 95 percent by weight, in which said ethoxylated alcohol is present in said aqueous dispersion in a quantity of between 0.5 to 50 percent by weight of the total weight of said amine and said ethoxylated alcohol.

6. A composition as claimed by claim 5 in which said alkylphenoxypo-ly (ethyleneoxy) alkanol is nonylphenoxypoly (ethyleneoxy) ethanol.

7. A composition as claimed by claim 5 in which said amine is octadecylamine.

8. A composition according to claim 5 wherein said ethoxylated alcohol is present in said aqueous dispersion in a quantity of between 3 to 30% by weight of the total weight of said amine and said ethoxylated alcohol, and said amine and said ethoxylated alcohol constitute from 0.5 to 30% by weight of said composition.

9. A composition according to claim 8 wherein said ethoxylated alcohol is nonylphenoxypoly (ethyleneoxy) ethanol containing about 40 moles of ethylene oxide and said amine is octadecylamine.

References Cited UNITED STATES PATENTS 2,649,415 8/1953 Sund berg et al. 252-392 2,840,549 6/1958 McNulty et al. 260 2,956,889 10/1960 Denman 252--392 LEON D. ROSDOL, Primary Examiner.

J. GLUCK, Assistant Examiner.

U .S. C1.X.R. 

